1. Field
The disclosed concept pertains generally to electrical switching apparatus and, more particularly, to bi-directional direct current electrical switching apparatus, such as, for example, circuit breakers including an arc chute.
2. Background Information
Electrical switching apparatus employing separable contacts exposed to air can be structured to open a power circuit carrying appreciable current. These electrical switching apparatus, such as, for instance, circuit breakers, typically experience arcing as the contacts separate and commonly incorporate arc chutes to help extinguish the arc. Such arc chutes typically comprise a plurality of electrically conductive plates held in spaced relation around the separable contacts by an electrically insulative housing. The arc transfers to the arc plates where it is stretched and cooled until extinguished.
Typically, molded case circuit breakers (MCCBs) are not specifically designed for use in direct current (DC) applications. When conventional alternating current (AC) MCCBs are sought to be applied in DC applications, multiple poles are electrically connected in series to achieve the required interruption or switching performance based upon the desired system DC voltage and system DC current.
One of the challenges in DC interruption is to drive the arc into the arc interruption chamber, specifically at relatively low current levels. Some existing DC switching devices use permanent magnets to drive the arc into the arc splitter plates. However, they either provide only uni-directional current interruption, or they are relatively large due to the use of two separate arc chambers in order to achieve bi-directional performance.
There is room for improvement in bi-directional direct current electrical switching apparatus.